K-9 Mail AlternativesOnly apps categorised as Email Clients

The best Email Client alternative to K-9 Mail is Thunderbird, which is both free and Open Source. If that doesn't suit you, our users have ranked more than 25 alternatives to K-9 Mail and many of them are Email Clients so hopefully you can find a suitable replacement. Other interesting Email Client alternatives to K-9 Mail are Betterbird, FairEmail, Evolution and Microsoft Outlook.

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K-9 Mail alternatives are mainly Email Clients, but if you're looking for Calendar Apps or Contact Managers you can filter on that. Other popular filters include iPhone, Windows, Linux, Android and Android + Open Source. These are just examples - use the filter bar below to find more specific alternatives to K-9 Mail.
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Alternatives list

  1. Thunderbird icon

    Thunderbird

     2530 likes
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    Cross-platform email client supporting multiple identities, chat, and strong filtering. Extend functionality with add-ons like RSS/Atom feed readers and PGP support.

    86 Thunderbird alternatives

    Cost / License

    Application types

    Platforms

    • Mac
    • Windows
    • Linux
    • Android
    • BSD
    • AppImageHub
    • Snapcraft
    • Flathub
    • PortableApps.com
    • F-Droid
    • Haiku
    • Homebrew
    • Chocolatey
    Thunderbird screenshot 1
     
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    37
    Comments about Thunderbird as an Alternative to K-9 Mail
    Tubby 9417
    Positive
    0

    A really great client used by many, popular because it supports almost every mail provider (not proton ?), and mail providers provide documentation to integrate with Thunderbird. I recommand

    Diatomee
    0

    Afaik the Thunderbird for Android and K-9 mail are developed by the same team now and have the same infrastructure under the hood, therefore it doesn't make any difference which one you choose.

    K-9 Mail Icon
    Thunderbird icon

    • Most users think Thunderbird is a great K-9 Mail alternative.

    • Thunderbird is the most popular Windows, Android, Mac & Linux alternative to K-9 Mail.

    • Thunderbird is the most popular Open Source & free alternative to K-9 Mail.

    • Thunderbird is Free and Open SourceK-9 Mail is also Free and Open Source
    • Thunderbird is CustomizableK-9 Mail is not according to our users
  2. Betterbird icon

    Betterbird

     70 likes
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    Betterbird, a soft fork of Mozilla Thunderbird, improves user experience with advanced features, bug fixes, security patches, and multi-row descriptions similar to Outlook. Compatible with multiple platforms and can be used alongside Thunderbird, sharing the same profile.

    28 Betterbird alternatives

    Cost / License

    • Free
    • Open Source

    Application type

    Platforms

    • Mac
    • Windows
    • Linux
    • Flathub
    • Chocolatey
    Betterbird screenshot 1
     
  4. FairEmail icon

    FairEmail

     87 likes
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    Open-source, privacy-focused email client offering features such as encryption via OpenPGP and S/MIME, unlimited accounts, a unified inbox, customizable settings, and reformatted emails to prevent phishing. Supports two-way synchronization and provides Pro features for additional customization.

    43 FairEmail alternatives

    Cost / License

    • Freemium (Pay once)
    • Open Source (GPL-3.0)

    Application type

    Platforms

    • Android
    • Android Tablet
    • F-Droid
    Compose message view.
    Setup screen.
    Messages view with dark theme.
     
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    19
    Comments about FairEmail as an Alternative to K-9 Mail
    LongLife
    Positive
    0

    Both are opensource, privacy oriented, free email clients for Android

    K-9 Mail Icon
    FairEmail icon

    • Almost everyone thinks FairEmail is a great K-9 Mail alternative.

    • FairEmail is the most popular Android Tablet alternative to K-9 Mail.

    • FairEmail is Freemium and Open SourceK-9 Mail is Free and Open Source
    • FairEmail is CustomizableK-9 Mail is not according to our users
  5. Ad
    Screenshot
    Infomaniak kMail icon
    Infomaniak kMail

    Privacy-focused Swiss email system provides 20 GB free storage, supports custom domains and unlimited storage, syncs contacts and calendars, is ad-free, and is part of a secure productivity suite used by over a million users acro...

    https://www.infomaniak.com
    Learn More
  6. Evolution icon

    Evolution

     205 likes
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    Evolution is a personal information management application that provides integrated mail, calendaring, address book and task list functionality.

    69 Evolution alternatives

    Cost / License

    Application types

    Platforms

    • Linux
    • BSD
    • Flathub
    • S/MIME
    • GNOME
    • OpenPGP
    Mail
     
  7. Microsoft Outlook icon

    Microsoft Outlook

     397 likes
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    Streamline emails, calendars, contacts, and task management with a smart inbox prioritizing critical messages. Includes calendar scheduling, third-party app integration like Facebook, Dropbox, and Trello, and support for Microsoft Exchange, Outlook.com, and Gmail, ensuring efficient task and email handling.

    126 Microsoft Outlook alternatives

    Cost / License

    • Pay once or Subscription
    • Proprietary

    Application types

    Platforms

    • Mac
    • Windows
    • Online
    • Android
    • iPhone
    • Android Tablet
    • iPad
    • Apple Watch
    • Android Wear
    Outlook 365 on Windows
     
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    Comments about Microsoft Outlook as an Alternative to K-9 Mail
    Guest
    Negative
    5

    Microsoft Office Outlook has more vulnerabilities and so far, seems more of a memory hogger on my device than K-9 Mail. Thank you, K-9 Mail!

    Review by a new / low-activity user.
    Guest
    Negative
    0

    If you use outlook for another email it will strore the password on a Microsoft server

    Review by a new / low-activity user.
    K-9 Mail Icon
    Microsoft Outlook icon

    • This alternative is disputed. Microsoft Outlook is a legitimate K-9 Mail alternative, but it might have issues that some users think are important.

    • Microsoft Outlook is the most popular Web-based, iPhone & iPad alternative to K-9 Mail.

    • Microsoft Outlook is the most popular commercial alternative to K-9 Mail.

    • Microsoft Outlook is Paid and ProprietaryK-9 Mail is Free and Open Source
  8. Spark Mail icon

    Spark Mail

     137 likes
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    E-mail app with all the great features: swipes (long/short), snooze, add (multiple) attachments from the cloud, support for various e-mail services and more.

    62 Spark Mail alternatives

    Cost / License

    • Freemium (Subscription)
    • Proprietary

    Application type

    Platforms

    • Mac
    • Windows
    • Android
    • iPhone
    • iPad
    • Apple Watch
    Spark Mail screenshot 1
     
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    8
    Comments about Spark Mail as an Alternative to K-9 Mail
    abogawat
    Positive
    0

    Spark is one of the most polished email clients out there, with multi-platform support and an excellent feature set. The free version is good enough for most people.

    K-9 Mail Icon
    Spark Mail icon

    • Almost everyone thinks Spark Mail is a great K-9 Mail alternative.

    • Spark Mail is Freemium and ProprietaryK-9 Mail is Free and Open Source
  10. Mailspring icon

    Mailspring

     113 likes
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    Boost your productivity and send better email with Mailspring, a beautiful, fast email client for Mac, Windows, and Linux. Mailspring is free to use and an optional pro version adds read receipts, send later, reminders and more.

    43 Mailspring alternatives

    Cost / License

    • Freemium (Subscription)
    • Open Source (GPL-3.0)

    Application type

    Platforms

    • Mac
    • Windows
    • Linux
    • Arch Linux
    • Fedora
    • Ubuntu
    Clean design with integrated search and swipe gestures
     
  11. Apple Mail icon

    Apple Mail

     244 likes
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    Access, view and manage messages from all your email accounts in one place. Categorize your messages into easy to browse categories. Catch up on email easily with Apple Intelligence powered Priority Messages and summarizations.

    105 Apple Mail alternatives

    Cost / License

    • Free
    • Proprietary

    Application type

    Platforms

    • Mac
    • Online
    • iPhone
    • iPad
    • Apple Watch
    Apple Mail screenshot 1
    Apple Mail screenshot 2
    Apple Mail screenshot 3
     
  12. Claws Mail icon

    Claws Mail

     106 likes
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    Email and news client on GTK+ foundation featuring quick performance, extensible plugins, secure protocols, advanced filtering, strong folder and contact management, lightweight design, powerful search, customizable interface, multi-language support, and encryption.

    62 Claws Mail alternatives

    Cost / License

    • Free
    • Open Source

    Application types

    Platforms

    • Windows
    • Linux
    • BSD
    The main window
     
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    6
  13. Infomaniak kMail icon

    Infomaniak kMail

     38 likes
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    Privacy-focused Swiss email system provides 20 GB free storage, supports custom domains and unlimited storage, syncs contacts and calendars, is ad-free, and is part of a secure productivity suite used by over a million users across Europe on all devices.

    42 Infomaniak kMail alternatives

    Cost / License

    • Freemium (Subscription)
    • Open Source (GPL-3.0)

    Application types

    Platforms

    • Online
    • Android
    • iPhone
    • Android Tablet
    • iPad
    • F-Droid
    Infomaniak kMail screenshot 1
     
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    1
    Comments about Infomaniak kMail as an Alternative to K-9 Mail
    Guest
    Negative
    0

    The Infomaniak client only works with Infomaniak mail accounts, while K-9 Mail supports all mail accounts that use the standard IMAP and SMTP protocols

    Review by a new / low-activity user.
    K-9 Mail Icon
    Infomaniak kMail icon
    • Infomaniak kMail is Freemium and Open SourceK-9 Mail is Free and Open Source
  14. Canary Mail icon

    Canary Mail

     28 likes
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    Canary can write your emails, prioritize what needs attention, silence spam & much more. Say hello to your Inbox Copilot!

    62 Canary Mail alternatives

    Cost / License

    • Freemium (Pay once or Subscription)
    • Proprietary

    Application type

    Platforms

    • Mac
    • Windows
    • Android
    • iPhone
    • Android Tablet
    • iPad
    • Apple Watch
    iOS-1
     
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  15. BlueMail icon

    BlueMail

     33 likes
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    BlueMail is a modern, mobile first, powerful Email management tool with a sleek design, unified inbox and support for all your accounts: IMAP,Exchange,POP3.

    32 BlueMail alternatives

    Cost / License

    • Free Personal
    • Proprietary

    Application type

    Platforms

    • Mac
    • Windows
    • Linux
    • Android
    • iPhone
    • Chrome OS
    • Android Tablet
    • iPad
    • Apple Watch
    BlueMail screenshot 1
    BlueMail screenshot 2
    BlueMail screenshot 3
     
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12 of 41 K-9 Mail alternatives